KR20100038315A - Construction machine - Google Patents

Abstract

[PROBLEMS] A construction machine where the temperature of a reduction agent in a reduction agent tank is controlled by a reduced number of parts and without installing a heat exchanger in the reduction agent tank. [MEANS FOR SOLVING PROBLEMS] The construction machine has a front working device driven by an engine (4), a urea SCR catalyst (20) placed in an exhaust route (19) of the engine (4) and reducing and purifying nitrogen oxides in exhaust gas, a urea water tank (23) for containing urea water supplied to the exhaust route (19), a temperature detector (24) for detecting the temperature of the urea water in the urea water tank (23), an air conditioner (21) for air conditioning an operation room (3), and warm/cold air guidance means for guiding, according to the temperature of the urea water detected by the temperature detector (24), warm/cold air ejected from the air conditioner (21) to the urea water tank (23). The warm/cold air guidance means includes a controller (31) for outputting, as a control signal, a cold air signal and a warm air signal corresponding to the temperatures of cold air and warm air ejected from the air conditioner (21).

Description

Construction machinery {CONSTRUCTION MACHINE}

The present invention relates to a construction machine such as a hydraulic excavator having a reducing agent tank in which a reducing agent supplied to an exhaust gas path of an engine is stored.

As a conventional technique of this kind, there is one disclosed in Patent Document 1. This conventional technique is used in a mobile vehicle having an engine, by injecting and supplying an aqueous solution of a reducing agent, for example, urea that easily generates ammonia, to the exhaust system of the engine to provide a concentration of NOx, which is nitrogen oxide in the exhaust gas. There is disclosed a configuration for reducing the temperature. It is further provided with a temperature detector for detecting the temperature of the urea water stored in the reducing agent tank, that is, the urea water tank, while branching from the engine's cooling water circulation passage, and providing a separate cooling water circulation passage continuous in the urea water tank. And a heat exchanger disposed in two separate three-way coke, cooling water circulation pump, electromagnetic valve and urea water tank in this separate cooling water circulation passage.

If the temperature of the urea water in the urea tank is high temperature, ammonia may be generated. On the contrary, if the temperature of the urea water is low temperature, it may freeze, which may interfere with the injection supply of urea water to the exhaust system of the engine. As a result, in the prior art configured as described above, the coolant of the engine when the temperature of the urine minority in the urea water tank detected by the temperature detector is higher than the predetermined temperature range and ammonia may be generated. By lowering the temperature of the urea water through the heat exchanger in the urea water tank, and conversely, the temperature in the urea water tank does not reach a predetermined temperature range, so that it is low enough to freeze. If present, the engine coolant is led to the above-mentioned separate cooling water circulation passage to raise the temperature of the urea water through the heat exchanger in the urea tank, thereby reducing the temperature of the urea water in the urea tank. In addition, it is maintained at a temperature within a predetermined temperature range that does not cause trouble by freezing. I'm trying to.

Patent Document 1: Japanese Patent Application Publication No. 2005-83223

The above-described prior art is arranged in two three-way coke, cooling water circulation pump, electromagnetic valve and reducing agent tank to maintain the temperature of the reducing agent consisting of urea water tank, that is, urea water in the reducing agent tank, within a predetermined temperature range. A heat exchanger or the like is required, the number of parts is large, the structure is complicated, and the production cost is likely to increase. In addition, as the number of parts increases, a large installation space corresponding to these parts is required, and in a construction machine that is likely to be restricted by the installation space, the installation of these parts tends to be difficult. Moreover, since the heat exchanger is arrange | positioned in a reducing agent tank, complicated maintenance work of this heat exchanger is needed, and maintenance cost tends to become high.

The present invention has been made in the above-described prior art, and its object is to achieve a temperature control of the reducing agent in the reducing agent tank with a small number of parts, and a construction that can be realized without installing a heat exchanger in the reducing agent tank. To provide a machine.

In order to achieve this object, the present invention provides an engine, a reduction catalyst for purifying and reducing nitrogen oxides in the exhaust gas, which is disposed in the exhaust gas path of the engine and has a working machine that operates in conjunction with driving of the engine; A construction machine comprising a reducing agent tank in which a reducing agent supplied to the exhaust gas path is stored, a temperature detector for detecting a temperature of the reducing agent in the reducing agent tank, the air conditioner for air conditioning the cab, and the detection by the temperature detector. According to the temperature of the said reducing agent, it is provided with the hot and cold wind inducing means which guides the hot and cold wind blown out from the said air conditioning apparatus to the said reducing agent tank.

According to the present invention constituted as described above, when it is detected by the temperature detector that the temperature of the reducing agent in the reducing agent tank is at a high temperature exceeding a predetermined temperature range, the hot and cold wind inducing means operates to reduce the cold air emitted from the air conditioning apparatus. The reducing agent tank can be cooled, thereby reducing the temperature of the reducing agent in the reducing agent tank so as to be within a predetermined temperature range. On the contrary, even when it is detected by the temperature detector that the temperature of the reducing agent in the reducing agent tank is at a low temperature not reaching a predetermined temperature range, the hot and cold wind inducing means operates to guide the warm air blown out of the air conditioning apparatus to the reducing agent tank. This reducing agent tank can be heated and the temperature of the reducing agent in a reducing agent tank can be raised so that it may become a temperature within a predetermined temperature range.

Thus, this invention is the construction machine provided with the air conditioning apparatus which air-conditions a cab, If it is a construction machine, the temperature detector which detects the temperature of the reducing agent in a reducing agent tank, and the hot and cold wind blown from an air conditioning apparatus through a hot / cold wind induction means to a reducing agent tank. By inducing, it is possible to realize temperature management for maintaining the temperature of the reducing agent in the reducing agent tank at a temperature within a predetermined temperature range. In addition, the hot and cold wind induction means induces a cooling means or a hot air of the air conditioning apparatus to a reducing agent tank, for example, processing means for performing a process of ejecting cold or hot air from the air conditioning apparatus in association with the temperature detected by the temperature detector. What is necessary is just to provide the ventilation path which consists of ducts, etc., Therefore, the temperature control of the reducing agent in this reducing agent tank can be implement | achieved with few components. In addition, since temperature control of this reducing agent can be performed by spraying cold air or warm air of an air conditioning apparatus to a reducing agent tank, for example, temperature control of this reducing agent can be implement | achieved without providing a heat exchanger in a reducing agent tank.

Further, in the above invention, in the above invention, the cold air signal and the warm air signal corresponding to the temperatures of the cold air and the warm air blown out from the air conditioning apparatus according to the temperature of the reducing agent detected by the temperature detector. A controller for outputting a signal as a control signal to the air conditioning apparatus, and a blowing path for directing cold air or warm air of the air conditioning apparatus to a reducing agent tank, wherein the controller includes the cold air when the temperature of the reducing agent is equal to or greater than a first predetermined temperature. The signal is output, and the warm air signal is output when the temperature of the reducing agent is equal to or lower than the second predetermined temperature lower than the first predetermined temperature.

According to the present invention configured as described above, the first predetermined temperature is set to a high temperature such that no ammonia is generated from the reducing agent tank in the high temperature region, and the second predetermined temperature is set to a low temperature such that the reducing agent in the reducing agent tank does not freeze in the low temperature region. What is necessary is just to set, and the temperature of the reducing agent in a reducing agent tank can be reliably maintained at the temperature within the predetermined temperature range higher than 2nd predetermined temperature and lower than 1st predetermined temperature.

Moreover, in this invention, in the said invention, the operation apparatus which operates the said air conditioning apparatus is provided in the said cab, and when this operation apparatus is operated, the said so that a part of the hot and cold wind blown out from the said air conditioning apparatus may be supplied to the said cab. It is characterized by including a switching means for switching the flow of hot and cold air of the air conditioning apparatus.

According to the present invention configured as described above, when the operating device in the cab is operated, the hot and cold air is guided from the air conditioning apparatus to the reducing agent tank through the hot and cold wind inducing means, and the reducing tank is cooled or warmed up through the switching means. A part of the hot and cold wind is supplied to the cab, whereby the cab can be air-conditioned.

Moreover, in this invention, the said reducing agent tank is accommodated in the said invention, It is characterized by including the thread formed by the partition cover.

According to the present invention configured as described above, even when the reducing agent overflows the reducing agent tank, for example, when the reducing agent is supplied to the reducing agent tank, the overflowing reducing agent is blocked by a compartment cover forming a thread, and leaks out of the thread. There is no work. Therefore, it is possible to prevent contact of the reducing agent with the apparatus or the like arranged outside the yarn, and to prevent corrosion of the apparatus or the like by the reducing agent.

Moreover, in this invention, the said reducing agent tank was provided adjacent to the said cab, In the said invention, It is characterized by the above-mentioned.

According to the present invention configured as described above, the distance between the air conditioner and the reducing agent tank can be set relatively short, and in the case of implementing the hot / cold air induction means, a ventilation path such as a duct to guide the hot / cold air of the air conditioner to the reducing agent tank It can be made small.

The present invention is equipped with an air conditioner for air conditioning the cab and a hot and cold wind induction means for directing the hot and cold winds emitted from the air conditioner to the reducing agent tank, so that the temperature control of the reducing agent in the reducing agent tank is realized with a small number of parts. This makes the structure simpler than in the related art, thereby making it possible to reduce the manufacturing cost. Moreover, since the number of parts is small, the installation space required for temperature management of the reducing agent in a reducing agent tank may be small compared with the past, and it is suitable also for the construction machine which is easy to be limited by an installation space. In addition, it is not necessary to provide a heat exchanger in the reducing agent tank, thereby eliminating the need for complicated maintenance work of the heat exchanger, which has conventionally occurred, and can reduce the maintenance cost in comparison with the prior art.

BRIEF DESCRIPTION OF THE DRAWINGS It is a side view which shows one Embodiment of the construction machine which concerns on this invention.

It is a top view which shows the principal part of the turning body with which this embodiment is equipped.

3 is a diagram showing a relationship between the temperature in the urea water tank and the output signal from the controller, which are stored in the controller provided in the present embodiment.

[Description of the code]

2: swinging structure

3: Cab

4: engine

5: engine compartment

7: boom

8: arm

9: bucket

10: boom cylinder

11: arm cylinder

12: bucket cylinder

19: exhaust gas path

20: urea SCR catalyst (reduction catalyst)

21: air conditioning unit

23: urea water tank (reducing agent tank)

24: temperature detector

25: compartment cover

26: thread

27: first blowing path (switching means)

28: operation device

29: switchgear (switching means)

30: second blowing path (hot and cold wind inducing means)

31 controller (hot and cold wind induction means) (switching means)

EMBODIMENT OF THE INVENTION Hereinafter, the best form for implementing the construction machine which concerns on this invention is demonstrated based on drawing.

BRIEF DESCRIPTION OF THE DRAWINGS The side view which shows one Embodiment of the construction machine which concerns on this invention, FIG. 2 is a top view which shows the principal part of the turning body with which this embodiment is equipped, FIG. 3 is an element memorize | stored in the controller with which this embodiment is equipped. It is a figure which shows the relationship between the temperature in a water tank, and the output signal from a controller.

This embodiment is a hydraulic excavator, for example, as shown in FIG. 1, and is provided with the traveling body 1 and the turning body 2 arrange | positioned on this traveling body 1. On the swinging structure 2, the cab 3 is provided in the front position, and the engine compartment 5 in which the engine 4 is accommodated in the rear position of the cab 3 is provided, and a weight balance is provided at the rear end. A counter weight 6 to be secured is provided. Moreover, the boom 7 rotatably mounted to the revolving body 2 in the up-down direction, the arm 8 rotatably mounted in the up-down direction at the front-end | tip of this boom 7, and the arm 8 of The front end is provided with the bucket 9 rotatably mounted in the up-down direction. Moreover, actuators, such as the boom cylinder 10 which operates the boom 7, the arm cylinder 11 which operates the arm 8, the bucket cylinder 12 which operates the bucket 9, etc. are provided. Moreover, the boom 7, the arm 8, the bucket 9, the boom cylinder 10, the arm cylinder 11, and the bucket cylinder 12 are comprised of the front work machine which can implement an excavation work | work. .

As shown in FIG. 2, on the swinging structure 2, the fuel tank 13 and the hydraulic oil tank 14 are disposed at the transverse position of the cab 3. Moreover, in the engine chamber 5, the hydraulic pump 15 which drives by the engine 4 and discharges the hydraulic oil which operates the actuator which comprises the above-mentioned front work machine is arrange | positioned. Further, an upstream side of the engine 4, a condenser 16 for cooling the refrigerant compressed by the compressor 18 attached to the engine 4, and a heat exchanger unit 17 such as a radiator are disposed. In the exhaust gas path 19, a reduction catalyst for reducing NOx, which is nitrogen oxide in the exhaust gas, for example, a urea SCR catalyst 20 is disposed.

In the cab 3, an air conditioner 21 for air conditioning the cab 3 is arranged. The hot and cold air of the air conditioning apparatus 21 is guided into the cab 3 by the first blowing path 27 made of a duct or the like. The engine 4 and the air conditioner 21 are connected by a coolant path 22 that guides the engine coolant.

In addition, for example, a chamber 26 in which a reducing agent tank, for example, the urea water tank 23 is stored, is provided adjacent to the cab 3, and the chamber 26 surrounds the urea water tank 23. Comprising a partition cover 25 is formed so that. In the urea water tank 23, the temperature detector 24 which detects the temperature of the reducing agent stored in this urea water tank 23, ie, urea water, is provided.

This embodiment is equipped with the hot and cold wind induction means which guides the hot and cold wind blown out from the air conditioning apparatus 21 to the urea water tank 23 especially according to the temperature of the urea water detected by the temperature detector 24. As shown in FIG. . This hot and cold wind induction means, for example, in accordance with the temperature of the urea water detected by the temperature detector 24, the air-conditioning device to the cold air signal and hot air signal corresponding to the temperature of the cold and hot air ejected from the air conditioning apparatus 21 And a second blowing path 30 composed of a controller 31 outputting as a control signal to the 21 and a duct for guiding the cold and warm air of the air conditioning apparatus 21 to the urea water tank 23, and the like. have.

In the above-described controller 31, for example, the relationship between the temperature in the urea water tank 23 shown in FIG. 3 and the output signal from the controller 31 is stored. In other words, the first predetermined temperature at which the temperature in the urea water tank 23 detected by the temperature detector 24 does not generate ammonia from the urea water tank 23 in the high temperature region, for example, about 40 ° C. At the temperature A, as the temperature increases, a cold wind signal having a value that gradually lowers the temperature of the blowing air is selected, and the temperature in the urea water tank 23 detected by the temperature detector 24 is low. When the urea water tank 23 in the region is at a low temperature such that the urea water tank 23 is not frozen, for example, at a second predetermined temperature of about -10 ° C, a warm air signal having a value for gradually raising the temperature of the blowing air in accordance with the decrease in the temperature. The relationship in which is selected is remembered.

Further, for example, the first blowing path 27 and the second blowing path 30 are communicated with each other, and the first blowing path is generated in accordance with the signal output from the controller 31 in the first blowing path 27. Means for communicating and blocking the path 27, for example, an on-off valve 29, are disposed. Moreover, the operation apparatus 28 which operates the air-conditioning apparatus 21 is arrange | positioned in the cab 3.

When the operating device 28 is operated, the first blowing path 27, the opening and closing valve 29, and the controller 31 described above are ejected from the air conditioning apparatus 21 even during the operation of the above-mentioned hot and cold wind inducing means. The switching means for switching the flow of the hot and cold wind of the air conditioning apparatus 21 to supply a part of the hot and cold wind into the cab 3 is configured.

In this embodiment comprised in this way, when pressure oil is supplied from the hydraulic pump 15 to the actuator which comprises a front work machine with the drive of the engine 4, for example, the boom 7, the arm 8, and the bucket ( 9) is selectively operated, such as excavation work is carried out.

Further, when the exhaust gas of the engine 4 is guided to the exhaust gas path 19 and the urea water stored in the urea water tank 23 is supplied to the exhaust gas path 19 by an injector (not shown), the exhaust gas is exhaust gas. NOx, which is the nitrogen oxide in the gas, is reduced and purified by the urea SCR catalyst 20, and the exhaust gas whose concentration of NOx is reduced is discharged to the outside as indicated by the arrow 32 in FIG.

In addition, when the temperature in the temperature detector 23, ie, the temperature of urea water, is higher than the 2nd predetermined temperature B shown in FIG. 3, and it is a temperature within the predetermined temperature range lower than the 1st predetermined temperature A, an example will be given. For example, the cold wind signal and the warm air signal are kept from being output from the controller 31. Therefore, when it is maintained in such a state, unless the operating apparatus 28 in the cab 3 is operated, the air conditioning apparatus 21 will be kept in the stopped state.

In the state where the temperature of the urea water is maintained at a temperature within a predetermined temperature range in this manner, when the operating device 28 is operated, the air conditioning device 21 is transferred from the controller 31 to the air conditioning device 21. A signal for activating a signal is output, and a signal for switching the opening / closing valve 29 of the first blowing path 27 from closed to open is output from the controller 31. Thereby, cold air or warm air is supplied from the air conditioning apparatus 21 into the cab 3 as shown by the arrow 33 through the first blowing path 27, and the cab 3 is air-conditioned. In addition, cold air or warm air of the air conditioning apparatus 21 is sprayed also to the urea water tank 23 as shown by the arrow 34 through the 2nd blowing path 30, for example. Therefore, the urea water in the urea water tank 23 is maintained at a temperature within a predetermined temperature range, but is cooled by the cold air from the air conditioning apparatus 21 or maintained in a state warmed by the warm air. When the operation of the operating device 28 is stopped, a signal for closing the open / close valve 29 is output from the controller 31. Thereby, the open / close valve 29 is switched to the closed state which interrupts | blocks the 1st blowing path 27. As shown in FIG.

For example, the urea water tank 23 detected by the temperature detector 24 in a state where the operating device 28 is not operated and the opening / closing valve 29 blocks the first blowing path 27. When the temperature of the urea water in the () is equal to or higher than the first predetermined temperature A in FIG. 3, a cold wind signal is output from the controller 31 to the air conditioner 21. As a result, cold air of a temperature corresponding to the cold air signal is ejected from the air conditioning apparatus 21. The cold air is injected into the urea water tank 23 as indicated by the arrow 34 through the second blowing path 30. As a result, the urea water tank 23 is cooled, and the temperature of the urea water in the urea water tank 23 decreases. When the temperature of the urea water detected by the temperature detector 24 reaches a temperature within a predetermined temperature range lower than the first predetermined temperature A, the air conditioning apparatus 21 is transferred from the controller 31 to the air conditioning apparatus 21. A control signal is output to stop the operation of the. Thereby, the air conditioner 21 stops and the blowing of cold air from the air conditioner 21 stops. By this operation, generation of ammonia from the urea water tank 23 is suppressed.

For example, in the state where the operating device 28 is not operated and the opening-closing valve 29 is blocking the 1st blowing path 27, it is detected by the temperature detector 24 on the contrary to the above-mentioned. When the temperature of the urea water in the urea water tank 23 is equal to or lower than the first predetermined temperature B in FIG. 3, a warm air signal is output from the controller 31 to the air conditioner 21. As a result, the air conditioner 21 is operated so that the warm air at a temperature corresponding to the warm air signal is ejected from the air conditioner 21. The warm air is injected into the urea water tank 23 as indicated by the arrow 34 through the second blowing path 30. Thereby, the urea water tank 23 warms up, and the temperature of the urea water in this urea water tank 23 rises. When the temperature detected by the temperature detector 24 reaches a temperature within a predetermined temperature range higher than the second predetermined temperature B, the operation of the air conditioning apparatus 21 is performed from the controller 31 to the air conditioning apparatus 21. A control signal for stopping is output. As a result, the air conditioner 21 stops, and the blowing of the warm air from the air conditioner 21 stops. By this operation, freezing of urea water in the urea water tank 23 is suppressed.

Further, for example, in a hot weather or the like having a high environmental temperature, the temperature of the urea water detected by the temperature detector 24 is equal to or greater than the first predetermined temperature A, and the air conditioning apparatus is controlled by the cold wind signal from the controller 31. When cold air is being injected from the 21 to the urea water tank 23, when the operating device 28 is operated, a signal for operating the opening / closing valve 29 is output from the controller 31. The open / close valve 29 is opened by this, and a part of cold air blown out from the air conditioning apparatus 21 is supplied to the cab 3 as indicated by the arrow 33 through the first blowing path 27. Thereby, while the urea water tank 23 is cooled, the inside of the cab 3 is cooled.

For example, in cold weather etc. where the environmental temperature is very low, the temperature of the urea water detected by the temperature detector 24 is equal to or less than the second predetermined temperature B, and is air-conditioned by the warm air signal from the controller 31. When the warm air is being injected from the device 21 to the urea water tank 23, when the operating device 28 is operated, a signal for operating the open / close valve 29 is output from the controller 31. As a result, the opening / closing valve 29 is opened, and a part of the warm air blown out from the air conditioning apparatus 21 is also supplied to the cab 3 as indicated by the arrow 33 through the first blowing path 27. As a result, the urea water tank 23 is warmed and the cab 3 is warmed up.

According to the present embodiment configured as described above, when it is detected by the temperature detector 24 that the temperature of the urea water in the urea water tank 23 is higher than the temperature within the predetermined temperature range, The cold air blown out from the air conditioning apparatus 21 through the air blowing path 30 is guided to the urea water tank 23 to cool the urea water tank 23, whereby the urea water in the urea water tank 23 The temperature may be such that it is within a predetermined temperature range. On the contrary, even when it is detected by the temperature detector 24 that the temperature of the urea water in the urea water tank 23 is at a low temperature which does not reach a temperature within a predetermined temperature range, the warm air emitted from the air conditioning apparatus 21 The urea water tank 23 is led to the urea water tank 23 to be heated, whereby the temperature of the urea water in the urea water tank 23 can be a temperature within a predetermined temperature range. Generation of ammonia from 23) and freezing of urea water can be suppressed. Therefore, the damage by ammonia can be prevented and the excellent exhaust gas treatment can be realized.

In particular, the present embodiment merely includes the controller 31 and the second blowing path 30, that is, in addition to the controller 31 that is usually installed, the second blowing path 30 made of a duct or the like may be provided. With only a small number of parts, temperature management of the urea water in the urea water tank 23 can be realized, so that the structure is simple and the production cost can be reduced. In addition, since the number of parts can be reduced, the installation space may be small, and therefore, the installation space can be installed in a small hydraulic excavator or the like which is easily constrained by the installation space. In addition, it is possible to realize temperature management of urea water without installing a heat exchanger in the urea water tank 23, thereby reducing maintenance costs without requiring complicated maintenance work of the heat exchanger. have.

Moreover, since the opening / closing valve 29 which opens and closes the 1st blowing path 27 by the signal output from the controller 31 with the operation of the operation apparatus 28 was provided, the air-conditioning apparatus 21 is operated and the element is operated. Even in the state of injecting hot and cold air into the water tank 23, the air conditioning in the cab 3 can be realized by operating the operating device 28, so that the air conditioning in the cab 3 is not disturbed. .

In addition, since the urea water tank 23 is accommodated in the seal 26 surrounded by the partition cover 25, when the urea water is supplied to the urea water tank 23, the urea water tank 23 Even when overflowed outside, the overflowed urea water is blocked by the partition cover 25 forming the seal 26 and does not leak out of the seal 26. The contact of the urea water can be prevented, and the urea water can prevent corrosion of equipment or the like outside of the seal 26.

In addition, since the urea water tank 23 is provided adjacent to the cab 3, the distance between the air conditioner 21 and the urea water tank 23 disposed in the cab 3 can be set relatively short, so as to provide a duct or the like. The 2nd blowing path 30 which consists of these can be made small.

In addition, although the said embodiment is equipped with urea water as a reducing agent, such a reducing agent may be ammonia water.

Claims (5)

A reduction catalyst for purifying and reducing nitrogen oxides in the exhaust gas, which is disposed in the exhaust gas path of the engine, and which has an engine, a work machine operating in conjunction with the driving of the engine, and a reducing agent supplied to the exhaust gas path include: In the construction machine provided with a reducing agent tank to be stored and a temperature detector for detecting the temperature of the reducing agent in the reducing agent tank, And an air conditioner for air conditioning the cab, and hot and cold wind inducing means for directing the hot and cold winds emitted from the air conditioner to the reducing agent tank in accordance with the temperature of the reducing agent detected by the temperature detector. machine. The hot and cold wind inducing means of claim 1, A controller for outputting a cold wind signal and a hot wind signal corresponding to the temperatures of the cold air and the hot air emitted from the air conditioning apparatus as control signals for the air conditioning apparatus according to the temperature of the reducing agent detected by the temperature detector; A blowing path for inducing cold or warm air of the air conditioning apparatus to a reducing agent tank, The controller outputs the cold wind signal when the temperature of the reducing agent is greater than or equal to the first predetermined temperature, and outputs the warm air signal when the temperature of the reducing agent is less than or equal to the second predetermined temperature lower than the first predetermined temperature. , Construction machinery. The air conditioner according to claim 1, wherein an operating device for operating the air conditioning device is provided in the cab, and when the operation device is operated, the air conditioner is turned on so as to supply a portion of the hot and cold air blown out from the air conditioning device to the cab. And a switching means for switching the flow of cold wind. The construction machine according to claim 1, wherein the reducing agent tank is housed and provided with a seal formed by a partition cover. The construction machine according to claim 1, wherein the reducing agent tank is provided adjacent to the cab.

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